French President François Hollande said that Europe needs to be more vigilant about the radicalization of its citizenry after the appearance of several Europeans in the video showing the execution of American aid worker Abdul-Rahman Kassig.

This still image taken from the video published online by the Islamic State group militants and made available Sunday shows a militant that the French government say is Frenchman Maxime Hauchard. The French government said Tuesday that a second Frenchman also appeared in the video.

French President François Hollande confirmed Wednesday that a second French militant appears in the video showing the beheading of an American aid worker and 18 Syrian prisoners by the self-declared Islamic State.

French prosecutors announced Monday that Abou Abdallah Al-Faransi, a native of Normandy born as Maxime Hauchard, was one of the two suspected Frenchmen who appeared in the video released Sunday. The clip showed the execution of several prisoners, whom the militants described as Syrian pilots, as well as the severed head of American aid worker Abdul-Rahman Kassig, known as Peter Kassig before he converted to Islam.

That the French militants appeared unmasked in the video was an unusually brazen move by the group. Wassim Nasr, an expert on jihad for France24, said the display of face was "to show the world that they have many ethnicities among their fighters. We see people from Asia, we see Europeans, Arabs, and their aim is to show they don't believe in ethnicities and nationalities and that their banner is Islam."

Government officials estimate that of the 1,000 French citizens who have fought in Syria and Iraq, 375 are currently there and at least 36 have died.

Meanwhile, British police are investigating claims that Nasser Muthana, a medical student from Cardiff, was also featured in the latest IS video. Muthana has previously been seen in the group's propaganda films, The Guardian reports. The group's videos also regularly include the man known as Jihadi John, who has only appeared masked but speaks with a London accent.

Earlier this month, Paris enacted an anti-terrorism law which will put a travel ban on anyone suspected of planning to wage jihad, AFP reports. Hollande said it was crucial that the full force of the law is used on those deciding to fight overseas.

"What is very important is not just reducing the number and avoiding new [foreign fighters], but have some sort of penalty applying to those who went to these areas because if you go to a combat zone it is something that should be subject to sanctions and penalties within the law," he said, according to AFP.